I have no experience hacking electronics. I only am comfortable with software, so please forgive me if my question sounds very amateur.

The problem I am trying to solve is having a camera in the bathroom of my house turn on only when my brother is inside. I have an autistic brother who sneakily likes to throw stuff down the toilet when we're not looking. If I can catch him and show that we are recording him doing that, I think I can get him to stop. But of course, no one else in my family is ok with being recorded in the bathroom.

Attempting to use a webcam to real-time track the person in the bathroom and determine who's in it is very difficult to do since it is generally difficult to recognize a face unless it's a frontal view. Instead, ideally I would like to have installed fingerprint door locks on all the bathrooms. Upon detecting that my brother is entering, it can notify my server which can activate the camera.

I doubt that there is anything in the market which directly meets my needs, and I wonder about how feasible this is to do. I am also open to using RFID instead of the fingerprint device to signal to my server to deactivate the camera. Everything needs to be wireless since my computer is elsewhere, so I'm particularly uncertain as to how to convert the signal into a wireless one which my computer can recognize. My entire family would really really appreciate any advice!